Yes I have this The cellular service comes back and then he goes back out again.
The iPhone cellular service does not work. It goes out when I do the reset recovery mode and factory mode.
Question marked as
1.
Remove and reinsert the SIM card.
If it doesn't help visit your carrier, maybe the SIM card is damaged, ask for a replaced (new) card. Normally it is free.
Ask also to check if the SIM tray is bent, as even a tiny misalignment can cause the SIM card to not fully connect with the internal contacts in your iPhone.
2.
See these Apple articles below:
If you see No Service, Searching, or SOS on your iPhone or iPad
If you see No Service, Searching, or SOS on your iPhone or iPad - Apple Support
Manually update your carrier settings on your iPhone or iPad
Manually update your carrier settings on your iPhone or iPad - Apple Support
Update your network provider settings manually on your iPhone or iPad
Update your network provider settings manually on your iPhone or iPad – Apple Support (UK)
If you see a Cellular, Ultra Wideband, or Apple Pay Issue message after an iOS update or restart